Santa Clara, Cuba (CNN) -- Cuba commemorated the 57th anniversary Monday of the attack that started Fidel Castro's revolution, but President Raul Castro did not speak, unlike in the previous three years.

Fidel Castro, who temporarily ceded power to younger brother Raul after emergency intestinal surgery in 2006 and permanently stepped aside in 2008, also did not speak. There had been speculation he might attend Monday ceremony because he had made several TV and public appearances in recent days, the first since his illness.

Venezuelan President Hugo Chavez was the scheduled keynote speaker, but he canceled at the last minute, citing recent heightened tension with Colombia.

The ceremony was held this year at the tomb of revolutionary icon Ernesto "Che" Guevara, who was killed in Bolivia in 1967 and whose remains were returned to Cuba in 1997.

The July 26 anniversary marks the date in 1953 when Fidel Castro led a small group of supporters in an attack on the Moncada military barracks in Santiago, in eastern Cuba. The attackers were repelled and many were killed.

Castro was captured and imprisoned but was released in 1955 under an amnesty for political prisoners. He fled to Mexico before returning to Cuba in 1956 and successfully launching the guerrilla movement that brought him to power in January 1959.